The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgment or admission that any of the material referred to herein is or was part of the common general knowledge as at the priority date of the application.
Liquid-liquid extraction, also referred to as solvent extraction or partitioning, is a method used in hydrometallurgy to separate or extract compounds from one liquid phase into another liquid phase. This is accomplished by manipulating the relative solubilities of the compounds to be isolated in two or more liquids having differing characteristics, as is the case with an aqueous phase (such as water), and an organic solvent phase (such as an oil or immiscible organic solvent).
The term solvent extraction can also refer to the separation of a substance from a mixture by preferentially dissolving that substance in a suitable solvent. In such a case, a soluble compound may be separated from an insoluble compound or a complex matrix.
Although the term partitioning is sometimes used to refer to the underlying chemical and physical processes involved in liquid-liquid extraction, these terms as used herein should be considered synonymous.
In the field of solvent extraction or partitioning, several hydrometallurgical systems are known which incorporate systems for manipulating liquid flow streams and phases, and for separating, splitting, or isolating liquids or phases of liquids, and the desired compounds extracted by such systems. Typically, a mixture of an extractant in a diluent is used to extract a desired compound from one phase to another. In solvent extraction techniques this mixture is often referred to as the “organic” phase and entrained organics need to be removed or recovered from the eventual aqueous streams.
Many extraction processes make use of so-called mixer-settlers. Mixer-settlers are a type of mineral process equipment used in solvent extraction processes and consist of a first stage that mixes the phases together in an agitated tank (referred to as a mixer) followed by a quiescent settling stage, usually in the form of a gravity settling basin (settler) that allows the phases to separate by gravity. It is difficult to manage the flow of liquid in settlers to achieve sufficient separation and to also minimise the settler area. The flow of liquids needs to be as laminar as possible, as flow interruptions or turbulence can lead to co-mixing of phases and resultant losses in extraction efficiency. The settling stage allows the phases to separate, but achieving high flow velocities can disturb the flow and hamper the process of separation, making it inefficient. Typical settler stages utilise an organic launder at the downstream end of the settler. The organic launder has a vertical liquid-facing face whereby the organic phase passes over the top lip of the vertical liquid-facing face and the aqueous phase passes under the bottom edge of the vertical liquid-facing face of the organic launder.
It is one object of the present invention to provide a phase splitter, phase splitter assembly, and method which overcomes substantially one or more of the abovementioned problems associated with the prior art, or at least provides a useful alternative thereto.